Model and algorithm of batch production scheduling of cold mill
冷轧机组批量作业计划模型与算法

In the production scheduling for a cold mill, a great number of constraints in production process have to be considered, such as the variations of material width and thickness at the entrance and exit of two continuous rolling steel coils. The scheduling process is transformed to an asymmetric two-traveling-salesman problem; and the Pareto-based multiobjective optimization model is established. A Pareto multi-objective adaptive-ant-colony algorithm based on the Pareto non-dominated set is introduced for solving the multi-objective problem. The Pareto non-dominated set is constructed by means of the adaptive-ant-colony algorithm and the Pareto optimization approach, which is used to guide ants to find the optimal solution. The parameters used to search a new path are updated automatically. The pheromones are changed automatically by considering all of the objectives and the process of searching path. Finally the scheduling solution is obtained by taking account of all objectives according to the requirements of production technologies. A simulation is conducted for a cold rolling mill, and the results indicate that the proposed algorithm is effective.